Water loss and morphological changes during desiccation of the anhydrobiotic nematode Ditylenchus dipsaci

Abstract

Ditylenchus dipsaci is an anhydrobiotic nematode which can withstand direct exposure to extreme desiccation. Water loss has been determined gravimetrically and morphological changes quantified by light microscopy. Water loss occurs in two distinct phases, with a permeability slump 2 min after the onset of desiccation. The permeability slump remains after treatment with sodium azide or carbon dioxide but disappears after heat treatment. There is a marked decrease in body length during the first 2 min of desiccation but diameter decreases throughout the desiccation period, mainly as a result of a decrease in the thickness of the hyaline layer. These observations suggest that one mechanism by which the nematode controls water loss during desiccation is by narrowing the groove between annulations. They also provide measurements on living nematodes which can be compared with more detailed observations using electron microscope techniques.